نشریه بوم شناسی گیاهان زراعی
سال سیزدهم شماره 4 (پیاپی 50، زمستان 1396)

To determine the traits affecting grain yield, 10 bread wheat genotypes including Morvarid and Kohdasht cultivars and Lines of N-87-4, N-87-9, N-86-6, N-86-8, N-80-19, N-86-5, N-85-5 and Line 17 were planted in two separate experiments including environmental conditions without heat stress in 15 December, and heat stress conditions of 10 February in Gonbad Kavous Agricultural Research Station during 2011-2012. Genotypes were compared in a randomized complete block design with three replications andwith combined analysis. Interaction of heat stress and genotypes were significant for grain yield, spike length, number of fertile spike. Genotypes and heat stress effect in all recorded traits were significant. In both conditions, grain yield had a positive and significant correlation with number of fertile spikes. Stepwise regression showed that the number of fertile spikes in normal conditions 99.8% and in heat stress 97.1% of grain yield changes were explained. The path analysis showed that the number of fertile spike had the most direct effect on grain yield in both conditions. The cluster analysis categorized genotypes into two group in normal conditions and three groups in heat stress conditions. Therefore, the number of fertile spikes can be used indirectly in the selection of genotypes with high yield in both heat and normal conditions.

Application of plant growth regulators is one of the most important methods to reduce the effects of drought stress to obtain suitable growth under water deficit conditions. The currecnt research objective is investigat the effect of cycocel foliar application on alleviation of drought stress concequences on growth traits of barley cv. Kavir .The experiment was conducted as factorial in randomized complete block design with four replications. The experiment treatments included cycocel with concentrations of 500, 1000, 1500 mg/L, drought stress at three levels of normal irrigation, irrigation cut-off in stemming and flowering stage. Drought stress negatively affected all evaluated traits. Cycocel application under drought stress significantly increased yield and yield components and reduced plant height. Foliar application with 1500 mg/L concentration of cycocel caused the plant to be subjected to drought stress. Applying 1500 mg/L cycocel can be recommended to reach optimum grain yield of barley cv. Kavir subjected in drought stress.

To investigate the effect of indole acetic acid (IAA) and benzyl amino purine (BAP) on morphological and physiological traits of lemon balm, an experiment was conducted in a randomized complete block design with three replications in farm condition at Namin county, Ardebil province, Iran. Spraying was done using IAA and BAP in the rates of 100, 200 and 300 ppm. Application of IAA and BAP promoted plant height and branches length. However, the branches length was increased in low IAA concentrations. Leaf chlorophyll content was in maximum at 300 ppm of BAP and 100 ppm of IAA. Application of IAA increased canopy diameter. More IAA concentrations increased shadow diameter. Increasing in IAA concentrations caused reduction in node number. Number of lateral shoots increased in high concentration of BAP in addition, more plant biomass was produced in high concentrations of BAP and IAA. Foliar application of BAP caused increasing in number of leaf comparing IAA. Therefore, application of IAA and BAP can be considered as an appropriate option to improve yield in lemon balm.

To investigate the effect zeolite application in alleviation of drought stress in some rapeseed cultivars, a field experiment was conducted based on randomized complete block design in factorial-split plot experiment in Firoozkooh, Iran climate condition. Rapeseed cultivars consist of Kr18, Karaj1, Ks12, Goliath, Hyola401, Karaj2, Eagle, SW, Comet and Hyola420. Two factors including irrigation levels and zeolite application were placed in main plots and rapeseed cultivars assigned in subplots. Irrigation was applied in three levels of normal irrigation, irrigation cutting-off in flowering and podding stages. Zeolite applied as pre-plant in 8 tons/ha rate along with initial plowing adding to the soil. The yield components decreased under drought stress conditions and ultimately led to a significant decrement in seed yield. Application of zeolite resulted in increasing of seed yield and seed oil content. The highest seed yield was obtained in normal irrigation regardless of zeolite application. In zeolite application cases, the Kr18 cultivar had the highest yield, Eagle cultivar was better in case of zeolite lack. Therefore, in drought stress condition, it is recommended to use zeolite to prevent seed yield losses in rapeseed cultivars.

Proper application of N fertilizer and its optimization in plants is definitely important. To study the effect of different level of nitrogen fertilizer on some morphological and phytochemical traits of artichoke, an experiment was conducted in a randomized complete block design with three replications in field conditions during two consecutive years in Isfahan, Iran. Nitrogen fertilizer was applied in 100, 150, and 200 kg/ha net nitrogen from urea source. Morphological traits including stem height, number of leaves per plant and number of capitols per plant and phytochemical traits such as total phenol, total flavonoid and antioxidant activity were measured. Increasing of urea fertilizer rate from 0 to 200 kg/ha increased stem height, number of leaves and capitols per plant, but decreased total phenol and flavonoid and antioxidant activity. Although nitrogen is an essential element for growth and development of artichoke plant, the consumption of high levels of nitrogen fertilizer has negative effect on qualitative traits. Also, considering chemical fertilizers hazard in environment, it is recommended to use 100 kg/ ha N to achieve optimal yield in artichoke.

To investigate the earthworm role in bio-remediation of lead and cadmium heavy metals and changes in their adsorption trend in corn, a pot experiment was carried out as factorial based on randomized completely block design with three replications in 2011. The treated pots received 20 earthworm individuals with 0, 150 and 300 mg/kg of cadmium (Cd) and lead (Pb). The increase of Cd and Pb concentrations led to higher Cd and Pb accumulation in grains. Pb highly accumulated in roots; however, Cd root accumulation was 63% less. Also, an increment of 14% was observed in plant tolerance index in presence of earthworm up-taking considerable amount of Pb and Cd. More tolerated plants against Pb was because of higher Pb translocation to shoots than Cd. Higher concentrations of Pb and Cd in soils severely decreased earthworm population and increased their accumulation in earthworm, indicating the success of the earthworm in the bio-remediation of heavy metals. Furthermore, Pb accumulated in higher levels than Cd in earthworm bodies. Therefore, earthworm application is recommended in bio-remediation of soils contaminated to heavy metals.

To study the effect of irrigation and fertilizer levels on yield of roselle (Hibiscus sabdariffa L.), an experiment was conducted as split plot based on randomized complete block design with three replications in Iranshahr, Iran in 2016. Treatments were included irrigation intervals of 7, 14 and 21 days and fertilizer ratios were included 0:100, 75:25, 50:50, 25:75 and 100:0 manure and chemical fertilizers. Irrigation and fertilizer levels had a significant effect on most of roselle characteristics. Calyx yield with irrigation interval of 14 days, it was about 8.1 g/m2, which was increased to 10.6 g/m2 compared to 7 days irrigation interval. Integrated application of chemical fertilizer with manure was more incresing on roselle yield components than their separate application. The highest calyx yield was obtained in equal ratio of manure and chemical fertilizer, which was 23.7 and 32.2% higher than their individual application of manure and chemical fertilizer, respectively. Integrated application of manure and chemical produced more biomass. Therefore, application of equal ratio of manure and chemical fertilizer with irrigation intervals of 14 days in Iranshahr aquatic and climatic conditions is recommended for roselle cultivation.

In this study, the susceptibility of different larval instars of Colorado potato beetle, Leptinotarsa decemlineata to Biobit containing Bacillus thuringiensis var. tenebrionis Ber., as microbial and imidacloprid as novel chemicals and phosalone as conventional insecticides was investigated in laboratory conditions. Colorado potato beetles were propagated on potato leaves planted in pots and their 1st, 2nd, 3rd, and 4th larval instars’ susceptibility was determined by bioassay test. LC50 values of Biobit for L1, L2, L3 and L4 were defined as 252, 613, 1731 and 3006 ppm after 144 hours, respectively. Also, LC50 values for imidacloprid and phosalone after 72 hours were 17.58, 41.35, 56.76 and 81.27 ppm and 447, 698, 1020 and 1297 ppm, respectively. Older insect larvae were more resistant to microbial and chemical treatments. Also, Colorado potato beetle was more susceptible to imidacloprid then phosalone and Biobit.